Parody in particular has lots of precedence backing it up as Fair Use.
Fair Use is not a law, it's a legal defense that you may use during copyright litigation. It does not prevent the litigation from going forward.
And it's generally considered very, very hard to prove Fair Use if the defendant is making money directly off of whatever was made with the borrowed material. So, whereas a teacher who makes copies whole-clothe of newspaper articles doesn't make money directly off of sharing articles with students, a YouTuber putting up videos for ad revenue is.
Commentary also has a long tradition of being fair use. People sold newspapers with reviews in them and they were absolutely able to quote from the sources they were reviewing. Quoting 30 seconds of a half-hour show as part of a review seems to fit comfortably in the tradition of fair use, whether it's a commercial use or not.
